I work with IPC norms (27ç and 9701) in which cycling means less than 20 or 30°C/min and thermal shock more than these values. That is explain that you go faster.
Nevertheless your cycles should last at least 20 min = 2x 10min of dwell.
So 100,000 should represent 4 years.
For sure we cannot offers test lasting so long.
Grandrien
========================================
Message du 04/04/12 21:15
De : "Inge Hernefjord"
A : [log in to unmask]
Copie à :
Objet : Re: [TN] how to pass solder joint reliability of a 3.2 mm board (16 layers) for QFN packae
we tested for provoking failures for equipments that we must guarantee
minimum 20 years life. Either you can test lots of parts for a short time
(fewer cycles) or few parts under long periode (many cycles). We occupied a
temp cycling box for 1 1/2 year. Noone has done such a test before.
Personally, I regard these tests as exaggerated or even meaningless, but I
did not tell them. Myself, I had performed a step stress test. E.g. as
follows:
*Mil Std 883 Method 1010:*
- Must be conducted for a minimum of 10 cycles
- Condition A: -55 (+0/-10) C to 85 (+10,-0) C
- Condition B: -55 (+0/-10) C to 125 (+15,-0) C
- Condition C: -65 (+0/-10) C to 150 (+15,-0) C
- Condition D: -65 (+0/-10) C to 200 (+15,-0) C
- Condition E: -65 (+0/-10) C to 300 (+15,-0) C
- Condition F: -65 (+0/-10) C to 175 (+15,-0) C",
- Total Transfer Time <= 1 minute
- Total Dwell Time >= 10 minutes
- Specified Temp reached in <= 15 minutes
*JEDEC JESD22-A104:*
- Recommended for lot acceptance screen : 10 cycles
- Recommended for qualification: 1000 cycles
- Condition A: -55 (+0/-10) C to 85 (+10,-0) C
- Condition B: -55 (+0/-10) C to 125 (+10,-0) C
- Condition C: -65 (+0/-10) C to 150 (+10,-0) C
- Condition D: -65 (+0/-10) C to 200 (+10,-0) C
- Condition F: -65 (+0/-10) C to 175 (+10,-0) C
- Condition G: -40 (+0/-10) C to 125 (+10,-0) C
- Condition H: -55 (+0/-10) C to 150 (+10,-0) C
- Total Transfer Time <= 1 minute
- Total Dwell Time >= 10 minutes
- Specified Temp reached in <= 15 minutes
Much, much better way
Inge
On 4 April 2012 17:35, grandrien wrote:
> How can you peformed 100,000 cycles ? Cycles means slow heating/cooling
> rate, lower than 20 C/min. So each cycle should be minimum 30min, more
> probably about 1h. So it would represent 5 to 11 years.
> Where is my mistake ?
>
> ========================================
> Message du 03/04/12 20:25
> De : "Inge Hernefjord"
> A : [log in to unmask]
> Copie à :
> Objet : Re: [TN] how to pass solder joint reliability of a 3.2 mm board
> (16 layers) for QFN packae
>
>
> Can you develop your question so that a slow thinker like me can understand
> TMCL 1000 c on QFN8's is very mild, I suppose nothing will happen. I
> investigated QFN64's recently. They had passed 100,000 cycles with some few
> issues. This was a -55/125 C test.
> I think you should tell a little about the assembly, because that's what
> decides the result.
>
> Inge
>
> On 2 April 2012 18:55, jonathan noquil wrote:
>
> > Hi All
> >
> > Need some suggestions on how to handle solderjoint issue (How to tweak to
> > pass TMCL1000 cycles- 0 to 100C) on QFN packages ( 5 x 6 x 1.0 mm with 8
> > pins).
> > Finish is Pure Sn
> > Board is 16 layers 3.2 mm, HASL finish.
> >
> > Does someone had an experience to share?
> >
> > thanks
> >
> >
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